If the option exists in WHM, that's new. We have always done it manually.

There is something to realize here. Being authoritative for rdns (PTR records) is not the same as being authoritative for regular DNS. You must be assigned this either in a rwhois server or by having your IPs SWIP'd in the ARIN data base. Unless this is done, your PTR records will be ignored.

If you are authoritative for rdns, let me know and I'll walk you through it. You can also find me on AIM if you prefer (kwimberl).